Tape conductor



0. N. MINOT TAPE CONDUCTOR Filed Nov.

Dec. 13, 19 0 Fig. l

mxaysax INVENTQR. OTIS N. MINOT ATTORNEYS United States Patent TAPECONDUCTOR Otis N. Minot, 22 Eliot Road, Lexington 73, Mass.

Filed NOV. 16, 1956, S91. N0. 622,574

8 Claims. (Cl. 174-117) This invention relates in general to electricalconductors and consists in a novel conductor in the form of a thin flattape or strip useful in many types of electrical circuits.

An insulated electrical conductor in the form of a tape offers numerousadvantages. In particular, circuits may be easily run from one place toanother over supporting surfaces in a manner requiring minimum space andfacilitating concealment. Where a circuit must pass through a wall orpartition, thin flat conductors require only a slit or crack, and mayfrequently pass between a door and its jam. A further advantage of thetape form of conductor arises from the greatersurface-to-cross-sectional-area ratio it provides over a circularconductor, by which the dissipation of heat is greatly increased, andthe current carrying capacity of a given size conductor is enhanced.

A tape conductor providing these advantages should be such that circuitconnections may be made and then covered so as to be concealed andprotected easily. Not only should the conductor be readily exposed, itshould also be accessible in a manner that permits the making of aconnection to it. Preferably, therefore, the conductor is separable fromthe insulation so that a solder, crimp or pressure connection can bemade without destroying the insulation, and the insulation isadvantageously such that it may be reapplied to the conductor after theconnection has been made. A tape having these features should moreoverbe a rugged, flexible, easily installed item with which few, if any,special tools or techniques are required, and must above all beinexpensive.

In general the tape form conductor of this invention consists in a thinflat conductive strip which is sandwiched between layers of flexibleinsulating sheet material. These layers of sheet material form aninsulating covering for the conductive strip which also conceals andphysically protects the strip. The layers are of width greater than thestrip so as to project beyond its edge.

The insulating layers of the tape conductor are adhesively bondedtogether in a manner permitting them to be peeled apart. The strip isarranged to be carried by one of the layers when they are separated soas to be easily accessible. The conductive strip is accordinglyadhesively bonded to only one of the layers, or, alternatively, to bothof the layers with the adhesion toone being sufliciently stronger'thanthe adhesion to the other that the strip is carried entirely by the onewhen the layers are separated. The strip is preferably bonded to theinsulating layer in a manner permitting it to be peeled from the layer.

The layer carrying the conductor will usually be the cover layer whichwhen peeled from the other, or base, layer raises the conductor to anaccessible location. The conductor strip may then be peeled from thecover layer so that contact to it may be made.

The conductive strip may be any of numerous conductive materials in theform of a strip of foil or in the 2,964,587 Patented Dec. 13, 1960 formof particles arranged sufficiently densely as to carry a current. Thenumerous varieties of material and structure make it possible to formthe strip of varied electrical characteristics. Similarly the insulatinglayers may be formed of any flexible insulating sheet material and theadhesive combining the layers with each other and with the strip andhaving the desired characteristics may be any of those well-known in theart as suitable for combining the particular materials in the propermanner. In this connection the adhesive is preferably one characterizedas being normally tacky and pressure sensitive, and it is applied in amanner to be non-offsetting.

The tape conductor of this invention may include any of numerousmodifications. In its simplest embodiment it consists of a singleconductive strip located between two insulating layers, but in morecomplex forms two or more strips may be present. The outer layers ofinsulating material may carry an adhesive coating, e.g. ofpressure-sensitive adhesive, to facilitate mounting the tape conductoron a supporting surface over which it is to be run. One or both of theouter layers may also be per forated so that a part of the layer may betorn from the rest and peeled away to expose the conductive strip onlyin selected areas. To simplify the separation of the two layers, or thetearing of part of one layer from the rest, a cord may also be runbetween the layers such that when stripped out the layer is cut orseparated from the other layer. Alternatively separation of the layersmay be facilitated by offsetting the layers or by inserting between theman outwardly extending tab or strip having a surface of low adhesiveattraction.

The tape conductors of this invention are Well-suited for many types ofcircuits such as control circuits useful for lighting or as a powersupply for small motors, relay circuits, and circuits in electronicdevices. It should be of course recognized that a tape conductor, as anyconductor, is limited in its current carrying capacity by thecross-sectional area of the conductor, and in its voltage by the amountof insulation. In some cases the tape conductor will employ a thin foilof metal having low power capacity while in other cases the metal willbe thicker. The construction of tapes of this invention permitsconsiderable latitude in the dimensions of the conductor; for anyparticular use well-known circuit design standards may be applied indesigning or selecting a proper conductor. It is also contemplated thatin some cases the tape conductor of this invention may be used tointroduce resistance into a circuit. It may accordingly be desired thatthe conductive strips be moderately, or even poorly, conductive, and itmay for such uses be formed of a resistance material such as carbon orNichrome. The improved heat dissipating qualities of the tape conductorare advantageously utilized in such embodiments.

A conductor of this invention may readily be run over supportingsurfaces and through small openings in a manner permitting very simpleestablishment of any desired circuit layout with a minimum of cutting ofpartitions and without separate fasteners. The making of electricalconnections, either to the apparatus or equipment with the tapeconductors are used, or in joining one tape conductor with another, iseasily accomplished. As has been pointed out, the conductive strip maybe exposed and brought to an accessible location by peeling theinsulating layers apart, and the strip may, if desired, be stripped fromthe layer carrying it. Where thus exposed it may be joined to almost anytype of connection, as a post and thumbscrew, clip, or it may becrimped, soldered, or cold-pressure welded to make an electricalconnection.

Special sheet metal connectors formed with outward projections are alsovery useful in connecting one tape to another easily and with a minimumof .special equipment. A connector need only be placed between twoconductors which are to be connected, and the conductors are thenpressed together so as to be pierced by the projections which then bendaround the conductors and assure good electrical contact. The samepurpose may be served by the insertion of various other metal pieceshaving sharp points or edges which will make positive contact with theconductors.

The manufacture of the conductors of this invention is preferablycarried out by applying the adhesive to one or more of the insulatinglayers and then assembling them under pressure with the conductive stripbetween them. The non-adhesive surfaces of the insulating layers may betreated in well known manner to facilitate the peeling of the adhesivecoated face from them, so that the layers may be readily peeled apart toexpose the conductive strip or to peel the tape conductor from a roll.Where the tape conductor is to be adherent to a supporting surface thebase layer will carry an adhesive coating, preferably one that ispressure-sensitive, on its outer surface, and the inner surface ofeither the cover layer or the base layer will also carry a coating ofadhesive by which the cover and base layers are adhered together and bywhich the metallic strip is adhered to one of them. Since there are nowcommercially available many pressure-sensitive insulating tapes, thesemay Well be used in fabricating the tape conductors of this invention,by assembling one as the base layer and another as the cover layer withthe conductive strip between them. The adhesive of the cover layerserves to combine the assembly.

Commercially available tapes of this type are generally treated at theirback surfaces to reduce the adhesion of the adhesive layer to them.Because of this reduced adhesion to the back surface, the cover layermay be peeled from the base layer more easily than the base layer ispeeled from a supporting surface to which it is applied. Thisfacilitates the making of connections to the tape conductor after it hasbeen applied to its supporting surface, since the cover layer may beeasily removed from the base layer without pulling the base layer fromits supporting surface. Moreover, since the cover layer carries theadhesive which holds the conductive strip, peeling away the cover layerfrom the base layer also carries the conductive strip from the baselayer to an accessible location.

The invention is described in detail below with reference to preferredembodiments and modifications shown in the accompanying drawings inwhich:

Fig. 1 is a transverse cross-section of one embodiment of thisinvention;

Fig. 2 is a view in perspective of the embodiment shown in Fig. 1showing the cover layer peeled back with the metallic strip peeled fromit;

Fig. 3 is a schematic perspective view, partly cut away to revealstructural details, of a second embodiment of this invention;

Figs. 4 and 5 are respectively a perspective view and a side elevationillustrating a connection of two tape conductors utilizing a metallicinsert to join the strips.

In the embodiment the tape conductor consists of a conductive strip 10,of e.g. copper or aluminum foil, assembled between a base layer 12 and acover layer 14, each of an insulating sheet material. The cover layer 14is bonded by an adhesive coating 15 to the base layer 12 and the strip11) is adhesively bonded to the cover layer 14 but is unbonded to thebase layer 10. Thus when the cover layer 14 is stripped from the baselayer 12, as shown in Fig. 2, the strip 10 is carried by the cover layerfrom which it may be stripped, separately.

Both the cover layer 14 and the base layer 12 may be of any insulatingsheet material Well known to the art, e.g., coated paper, fabric, orplastic sheet materials such as cellulose, vinyl plastics, rubber or thelike. The adhesive material is most preferably one of those well knownin the art as a non-offsetting, tacky, pressure-sensitive adhesive so asto form a layer which will adhere securely to its carrying surface andprovide a peelable bond which retains its tackiness. The layers may thusbe separated from each other and from the conductive strip, while beingsubject to reassembly simply by pressing the components together again.

Where two like materials are adhesively combined face to face, as arethe base layer and cover layer, it may be necessary to treat the surfacethat does not carry the adhesive to reduce its affinity for the adhesiveand to prevent the adhesive from off-setting to it by means well-knownin the art. Both the base layer and cover layer may conveniently beformed from a commercial, pressure-sensitive, insulating tape materialobtainable in roll form. The back surface of such tape is generally ofreduced affinity for the adhesive layer carried on the other side, topermit easy unrolling of the tape without off-setting the adhesive. Sucha tape is well suited for use in this invention because of itsnon-offsetting properties.

In the embodiment shown in Figs. 1 and 2 the base layer 12 is providedwith an adhesive coating 16 on its outer surface. This coating permitsthe tape conductor to be applied to a supporting surface such as a wallor assembly panel. In this form, the tape conductor may conveniently beformed by combining two lengths of an electrical insulating tape eachhaving a non-off-setting, tacky, pressure-sensitive adhesive coating,with the adhesive layer 15 of the cover layer 14 being applied to theback (non-adhesive) surface of the base layer 12 and with a narrowconductive strip 10 inserted between the layers. When assembled, thecover layer 14 is peelably adhered to the base layer 12 and to the strip10, and may readily be separated to provide access to the strip. Tape ofthis form may be packaged in the form of rolls, from which runninglengths may be removed as needed. Advantageously the back of the coverlayer or the adhesive of the base layer may be such that the adhesiveaffinity of one for the other is reduced so as to reduce the possibilityof separating the cover layer from the base layer when the tape isunrolled. Or, alternatively, a liner of low adhesive affinity may beinserted, at any convenient stage of assembly, so that it lies betweenbase adhesive 16 and the cover layer 14.

In the embodiment shown in Fig. 3, the insulated tape conductor carriesa pair of conductive strips 10 between the base layer 12 and the coverlayer 14. Selective access to either or both strips is provided for bydividing the cover layer 14 into both longitudinal and transverse handsby perforations and by placing the adhesive in a manner that facilitatesseparation of the plies only in selected rows or columns.

As shown the cover layer 14 is divided into six longitudinal bands 14a-fby five lines of perforations 18, so that there is a band generallyoverlying each strip 10 and a band on each side. These perforations 18make it possible to raise only the band over the strip together with theunderlying strip, as in the manner shown at A. Alternatively wherecomplete separation of the conductors is desired, the tape may be rippedat the center row of perforations. A rip cord 19 underlying this row maybe provided to facilitate this separation.

The cover layer is also divided into transverse hands by lines ofperforations 20 so that access may be had to one or both of theconductors at a location other than at the ends of a length of tapeconductor. A transverse band of the cover layer 14 may thus be separatedfrom the base layer 12 to expose either or both of the conductivestrips, as shown in Fig. 3 at B.

The arrangement of the adhesive in this embodiment, as outlined by thedash lines, is designed to facilitate separation of the cover layer 14in certain of the bands while rendering separation more difficult inothers.

The adhesive is arranged so that the conductive strips 10 are adhesivelybonded to only the cover ply 14 and only in the regions of alternatetransverse bands, as in dicated at C. The regions of the othertransverse bands, which are designated to be most easily raised, are notbonded to the conductive strips. Similarly, the adhesive bonding of thecover layer 14 to the base layer 12 alternates between a strong bond anda weak bond (as suggested by the varying areas over which the adhesiveis shown to be applied) with the latter occurring in the transversebands designed for easy separation. These bands are thus most readilyseparated from the base layer as at B and from the conductive stripwhile the bordering bands are held securely down.

The application of adhesive in the embodiment illustrated in Fig. 3 isshown as being in a varying pattern to provide greater or lesseradhesive attachment in the desired manner. Where stronger attachment isdesired, the adhesive is applied in a wide pattern, and where weakerattachment is desired, the pattern is narrower. Alternatively, however,different adhesives may be applied in a non-varient strip to achieve thesame result, or the adhesive may be applied as discrete dots which areof high frequently and densely grouped where strong adhesion is desired,and sparsely grouped where the adhesion is to be weaker.

In Figs. 4 and 5 is shown one of several possible forms of a metallicconnector element useful in joining the metallic strips of two conductortapes. The connector 32 is in the form of a thin flat ductile metalplate from which pointed projections 33 are punched out and raised. Bystripping the metallic strips from between their base layers 12 andcover layers 14 and then assembling the strips one on each side of theconnector, a secure electrical contact may be made, with the spikesfirmly embedded in the strips. The cover and base layers may then bereapplied to form a covering of double thickness at the location of thesplice. As shown in Fig. 5, the projections are advantageously inclinedto form an acute angle with the body of the connector 32 so that theywill bend flat against the connector under compression. Preferably theprojections 33 are inclined in opposite directions outwardly toward theends of the connector. When pressed flat, the projections liedivergently and anchor the connector firmly in place.

The manufacture of tape conductor of this invention is preferablycarried out by applying the adhesive in any well-known manner to thecover layer, and, if desired, also to the base layer. The oppositesurfaces of these layers are advantageously treated in known manner toreduce the adhesion of the adhesive to them and to facilitate thepeeling away of the overlying layers. The cover layer 14 is thenassembled with the conductive strip 10, such as a strip of aluminum,copper or other foil, and with the base layer. The cover layer,conductive strip and base layer may be assembled simultaneously, as byfeeding them together into the nip of a pair of pressure rollers, or bycombining the components in succession.

Conveniently the cover layer and base layer are formed of ordinarypressure-sensitive adhesive tape commercially available in rolls andmanufacture of the tape conductor consists simply in assembling theconductive strip between the back side of one tape (the base layer) andthe adhesive side of another tape (the cover layer) and pressing theassembly together. The conductive strip is then adhered to the coverlayer in peelable manner and that layer becomes peelably secured to thebase layer. Since the back side of the base layer is generally treatedto be of reduced attraction of the adhesive to facilitate separationfrom the roll of tape, the assembly may be readily peeled apart, orre-rolled, without blocking or oflsetting.

A further modification consists in forming the conductive strip fromparticles of conductive or partially conductive material. This may bedone by applying a pow- '6 der of conductive particles as a strip to oneof the outer insulating layers, and then combining that layer with theother. The particles may for instance be applied to the adhesive surface15 of the cover ply 14, or an adhesive surface to receive and hold themmay be applied specially for that purpose. v I I The conductiveparticles may similarly be incorporated in a liquid vehicle and appliedto one of the insulating layers as a conductive ink or paint which willdry or 'set to form the conductive strip.

Where a tape of extreme flexibility is desired, the tape conductor ofthis invention may be creped to permit lateral bending. The assembledtape conductor may be creped by well-known means after it has beenassembled, or alternatively component, base and cover layers andconductive strip may be creped before assembly.

From the foregoing disclosure it is believed apparent that thisinvention provides a novel tape form of conductor which lends itself toa great variety of modifications, a representative few of which aredescribed herein in detail. It is contemplated that other modificationswill readily occur to those skilled in the art and that suchmodifications may be made without departing from this invention.

Having thus disclosed my invention and described in detail preferredembodiments thereof, I claim and desire to secure by Letters Patent:

1. An insulated electrical conductor comprising a long narrow tape-likebase layer of flexible insulating sheet material and an overlying longnarrow tape-like cover layer of flexible insulating sheet material, athin flat conductive strip between the inside surfaces of said layersextending longitudinally the full length of said layers, said stripbeing bonded to said cover layer in selected regions and unbonded tosaid cover layer in other regions and substantially less securely bondedto said base layer, pressure sensitive adhesive peelably bonding saidlayers together, adhesive on the outer side of said base layer, andparallel rows of perforations extending across said cover layer defininga tab crossing said strip Where said cover layer is unbonded to saidstrip such that said tab may be removed to expose a portion of saidstrip.

2. An insulated electrical conductor comprising a long narrow tape-likebase layer of flexible insulating sheet material and an overlying longnarrow tape-like cover layer of flexible insulating sheet material, athin flat conductive strip between the inside surfaces of said layersextending longitudinally the length of said layers, pressure sensitiveadhesive peelably adhering said layers together, pressure sensitiveadhesive peelably adhering said strip to said cover layer with theadhesion thereto being greater than to the base layer, and at least onepair of rows of perforations extending across said cover layer defininga tab which may be raised to expose the portion of said strip betweensaid rows.

3. An insulated electrical conductor comprising a long narrow tape-likebase layer of flexible insulating sheet material and an overlying longnarrow tape-like cover layer of flexible insulating sheet material, astrip of metal foil between the inside surfaces of said layers extendinglongitudinally the length of said layers, pressure sensitive adhesivepeelably adhering said layers together, pressure sensitive adhesivepeelably adhering said strip to said cover layer with the adhesionthereto being greater than to the base layer, and at least one pair ofrows of perforations extending across said cover layer defining a tabwhich may be raised to expose the portion of said strip between saidrows.

4. An insulated electrical conductor comprising a long narrow tape-likebase layer of flexible insulating sheet material and an overlying longnarrow tape-like cover layer of flexible insulating sheet material, astrip of metal foil between the inside surfaces of said layers extendinglongitudinally the length of said layers, pressure sensitive adhesive onthe inside surface of said cover layer peelably adhering said coverlayer to said base layer and to said strip, said strip beingsubstantially less securely bonded to said base layer than to said coverlayer, adhesive on the outer side of said base layer, and at least onepair of rows of perforations extending across said cover layer defininga tab which may be raised to expose the portion of said strip betweensaid rows.

5. An insulating electrical conductor comprising a long narrow tape-likebase layer of flexible insulating sheet material and an overlying longnarrow tape-like cover layer of flexible insulating sheet material, astrip of metal foil between the inside surfaces of said layers extendingthe length of said layers, pressure sensitive adhesive peelably adheringsaid layers together, pressure sensitive adhesive peelably adhering saidstrip to said cover layer in selected regions, said strip beingsubstantially unbonded to said cover layer in other regions and beingsubstantially less securely bonded to said base layer than to said coverlayer, and rows of perforations extending across said cover layerdefining a tab crossing said strip at said other regions whereby saidtab may be raised to expose a portion of said strip.

6. An insulated electrical conductor comprising a long narrow tape-likebase layer of flexible insulating sheet material and an overlying longnarrow tape-like cover layer of flexible insulating sheet material, atleast two parallel strips of metal foil between the inside surfaces ofsaid layers extending the length of said layers, pressure sensitiveadhesive peelably adhering said layers together, pressure sensitiveadhesive peelably adhering said strips to said cover layer in selectedregions, said strips being substantially unbonded to said cover layersin other regions and being substantially less securely bonded to saidbase layer than to said cover layer, and rows of perforations extendingacross said cover layer defining a tab crossing said strips at saidother regions whereby said tab may be raised to expose a portion of saidstrips.

7. The conductor defined by claim 6 wherein at least one row ofperforations is provided in the cover strip extending longitudinallybetween the strips of foil.

8. An insulated electrical conductor comprising a long narrow tape-likebase layer of flexible insulating sheet material and an overlying longnarrow tape-like cover layer of flexible insulating sheet material, atleast two parallel strips of metal foil between the inside surfaces ofsaid layers extending longitudinally the length of said layers, pressuresensitive adhesive on the inside surface of said cover layer peelablyadhering said cover layer to said base layer and to said strips, saidstrips being substantially less securely bonded to said base layer thanto said cover layer, at least one pair of rows of perforations extendingacross said cover layer defining a tab which may be raised to expose theportion of said strips between said rows, and a row of perforationsextending longitudinally of said cover layer between said strips.

References (lit ed in the file of this patent UNITED STATES PATENTS2,495,734 Katzman et al Ian. 31, 1950 2,771,385 Hunphner Nov. 20, 1956-2,804,416 Phillipsen Aug. 27, 1957' FOREIGN PATENTS 198,739 GreatBritain June 1,. 1923 403,688 Great Britain Dec. 18,. 1933 850,915France Sept. 25, 1939 920,487 France Jan. 4, 1947 700,459 Great BritainDec. 2, 1953 933,943 Germany Oct. 6, 1955

